Question

当接收到从单独的客户端程序转换为字符串的整数（事务ID）时，我的Java UDP服务器程序片段出现错误：

客户端：

// Sending transaction ID to server
sendData = String.valueOf(transID).getBytes();
sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, sportno);
clientSocket.send(sendPacket);

SERVER：

// Receive client's transaction ID
receiveData = new byte[1024]; // 1024 byte limit when receiving
receivePacket = new DatagramPacket(receiveData, receiveData.length);
serverSocket.receive(receivePacket); // Server receives packet "100" from client
String clientMsg = new String(receivePacket.getData()); // String to hold received packet
int transID = Integer.valueOf(clientMsg); // Convert clientMsg to integer
System.out.println("Client has sent: " + transID); // Printing integer before iteration

虽然客户端发送数据包很好，但在字符串到整数转换期间我收到此错误：

Exception in thread "main" java.lang.NumberFormatException: For input string: "100"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:580)
at java.lang.Integer.valueOf(Integer.java:766)
at server.main(server.java:46)

我也使用了类似结果的Integer.parseInt（clientMsg）。但是，只要我没有尝试将数据包转换为整数，该程序就可以将数据包打印为字符串值。

此外，虽然它在终端中显示了这一点，但当我将此错误消息复制+粘贴到此帖子中时，“100”后面跟着大量的“s”，我假设剩下的是空的来自receiveData变量的字节。

这些空值是我的程序失败的原因吗？如果没有，该程序还有什么其他原因失败？另外，有没有办法将事务ID整数发送到服务器而不首先将其转换为字符串以防止此错误？

Answer 1

尝试希望这是有效的

String receivedMsg = new String(receivePacket.getData(), receivePacket.getOffset(), receivePacket.getLength());

Answer 2

String clientMsg = new String(receivePacket.getData()); // String to hold received packet

问题出在这里。您通过忽略传入数据报的实际长度来追加垃圾。它应该是：

String clientMsg = new String(receivePacket.getData(), receivePacket.getOffset(), receivePacket.getLength()); // String to hold received packet

线程“main”中的异常java.lang.NumberFormatException：对于输入字符串：“100”

2 个答案: